(a) Field of the Invention
The present invention relates to a method of low-duty mode operation in a femto base station.
(b) Description of the Related Art
A femto base station refers to an ultra-small base station that manages a femtocell having a smaller service area than a macrocell. The femtocell serves to improve speech quality in an indoor space which the coverage of the macrocell cannot reach, and to share the load of the macrocell, and is able to reduce communication cost. However, the femtocell may degrade the performance of mobile stations MS in the femtocell and the macrocell due to interference with the macrocell. To solve this problem, the femto base station supports a low-duty mode LDM as well as a normal mode.
The femto base station enters the low-duty mode if there is no mobile station attached in the femto base station or all the mobile stations present in the femtocell are in an idle or sleep mode. The cycle of the low-duty mode has a pattern (hereinafter, referred to as a “low-duty mode cycle pattern”) in which an available interval AI and an unavailable interval UAI alternately appear. The femto base station operates in the low-duty mode cycle pattern. During an available interval, the femto base station may become active on the air interface for synchronization with a mobile station, paging, ranging, or data traffic transmission. During an unavailable interval, it does not transmit on the air interface.